Couchbase utilizes the Jepsen testing framework to ensure the database's durability and consistency through rigorous testing, particularly with the enhanced durability levels introduced in the 6.5.0 release. Jepsen tests Couchbase by simulating operations amidst chaos, like network partitions and process failures, to verify that acknowledged writes are never lost and that a sequential consistency model is maintained. The setup involves implementing Jepsen's abstractions, such as Database, Client, and Nemesis, tailored specifically for Couchbase, to test various failure scenarios and cluster operations. Challenges in testing arise from the vast number of potential cluster configurations and the processing time required by Jepsen's linearizability checker, leading to strategies that focus on critical parameters and frequent testing through a structured test suite hierarchy. This approach has successfully identified bugs, increasing confidence in Couchbase's ability to safeguard data, though continuous testing is crucial as Jepsen might expose issues after numerous runs.